Travis: Build also for another dev branch and not on Julia nightly anymore

[ranocha]

I know that I've argued to build on Julia nightly in the past, but I think we should skip this now. It just costs time, in particular when multiple PRs are modified at the same time, while the benefits are comparably low. I've added the dev branch since I want to target that one while developing Taal in #187 etc.

[codecov]

Codecov Report

Merging #196 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #196   +/-   ##
=======================================
  Coverage   91.60%   91.60%           
=======================================
  Files          31       31           
  Lines        6958     6958           
=======================================
  Hits         6374     6374           
  Misses        584      584           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 645fe4a...a169033. Read the comment docs.

[sloede]

What's the purpose/intent of the dev branch? Do you want to use it as some sort of staging environment for large changes that require multiple development passes but should eventually be merged to master in one single motion?

[ranocha]

Exactly! That's what I would like to do with Taal (#187).

[ranocha]

In particular since you wanted to merge MPI into master first and we will build on that for Taal.